In the hydrogen generator, a raw material containing an organic compound comprised of at least carbon and hydrogen is subjected to steam reforming by a reformer including a reforming catalyst layer. A hydrogen-containing gas is generated by this reforming reaction. When the amount of steam supplied to the reforming catalyst layer in the reforming reaction is inadequate as compared to the amount of the raw material supplied, only the raw material increases in temperature, and flows through the catalyst layer in the reformer and gas passages. Since the raw material contains as the main component the organic compound comprised of carbon and hydrogen, the raw material is thermally decomposed under this situation to be a carbon status, and the carbon deposits on the reforming catalyst and in the gas passages. This may cause a decrease in catalytic activity and clogging of the gas passages, thereby disturbing the operation of the hydrogen generator.
It is known that by intermittently carrying out combustion for heating the reformer until the temperature of an evaporator which supplies the steam to the reforming catalyst layer increases to a predetermined threshold or higher at the start-up of the hydrogen generator, the temperature of the reforming catalyst layer can be kept lower than the temperature at which the carbon deposition occurs (for example, see Patent Document 1 as a conventional example). When the temperature of the evaporator exceeds the predetermined threshold, the combustion continues, and water supply to the evaporator starts. This start-up method can prevent the reforming catalyst from deteriorating.
Patent Document 1: Japanese Laid-Open Patent Application Publication No. 2005-170784